My doctor told me that the crp test was 'a bad' test - what did he mean?

Nonspecific test: I am not sure what your doc meant by a 'bad' test. I can only speculate that he or she meant that the c reactive protein (CRP) test is non specific meaning it doesn't diagnose a specific disease but rather indicates a marker of inflammation in the body. Chronic elevation in CRP levels may indicate a chronic inflammatory disease state but can't specify a definite diagnosis.

Cardia crp: Is not a specific test for cardiac problems. Is elevated in association with an increase risk for cardiovasuclar disease (i.e., heart atack). What is more importatnt is your history (do you have htn, diabetes, are obesse, high cholesterol, family history of heart attack/stroke, have you had angina-heart attack etc) the more you have the higher the risk. So CRP is just a tool we use.